Yarn twist control apparatus and method



March 8, 1966 N. ROSENSTEIN YARN TWIST CQNTROL APPARATUS AND METHOD Filed Sept. 17, 1963 United States Patent 3,238,591 YARN TWIST CONTROL APPARATUS AND METHUD Nathan Rosenstein, West Hartford, Conn., assignor to Spunize Company of America Inc., Unionville, Conn., a corporation of Connecticut Filed Sept. 17, 1963, Ser. No. 309,534 Claims. (c1. 28--1) This invention relates to an apparatus and method for controlling the twist in yarn, and more particularly concerns an apparatus and method for overcoming the tendency of various forms of textile equipment to trap the twist in a yarn which is being moved continuously through the equipment, causing the twist to back up and to accumulate in situations where such accumulation is highly undesirable.

When a yarn is provided with a relatively low or medium twist, such as one-half turn per inch to five turns per inch, for example, and when this yarn is continuously drawn past a friction guide or tensioning devices, or nip rolls, or the like, the contact between the yarn and such devices has a tendency to strip back the twist, creating an accumulation of high twist on the upstream side of these devices. As the yarn continues to be drawn past such device, twist which has accumulated suddenly surges past such point, thus providing large variations of twist in the yarn as it is fed to the delivery point. Such variations are highly undesirable and often show up in the finished product as streaks, irregularities, and other imperfections.

Other forms of textile equipment similarly cause untwisting and surges with concentrations of twist, resulting in a non-uniformity of yarn, ranging from excessive twist to insufficient twist, One of the outstanding examples of such textile equipment is a pair of nip rolls such as the nip rolls utilized in crimpers, delivery rolls in twisters, tensioning devices and guides on warpers, tensioning devices and guides on knitting machines, and the like. When a yarn having a helical twist is forced into the nip between the rolls, the nip tends to engage a flattened part of the yarn and thus tends to cause the yarn to rotate reversely about its axis, at the upstream side of the nip rolls. Then, when a considerable twist has accumulated upstream of the nip rolls, a length of highly twisted yarn surges through the nip, resulting in a non-uniformity of the type just discussed.

Similar problems exist not only in stutfer box crimping, but in edge crimping, gear crimping, air crimping, twisting, Winding, warping, sizing and even in other textile operations such as knitting and the like.

It is, accordingly, an object of this invention to provide an apparatus and method for overcoming the difficulties referred to above. More specifically, it is an object of this invention to provide an apparatus and method for overcoming the tendency of yarn handling and guiding equipment to cause the twist in a twisted yarn to back up, to develop a local highly twisted section of yarn, and to permit that highly twisted section to surge past the textile equipment, producing a yarn having a non-uniform twist from one length to the next.

Other objects and advantages of this invention, including the simplicity and economy of the same, and the ease with which it may be applied to textile equipment of various types, will become apparent in further detail hereinafter and in the drawings of which:

FIG. 1 is a diagrammatic view in side elevation showing a typical crimping apparatus incorporating one specific form of apparatus constructed in accordance with this invention;

FIG. 2 represents a view in side elevation of a preferred form of attachment constructed in accordance with this invention for incorporation into a crimping machine;

FIG. 3 represents a schematic view in side elevation, illustrating the manner in which a twisted yarn tends to accumulate a high degree of twist upstream of a pair of crimping rolls; and

FIG. 4 represents a view in side elevation showing an application of this invention to a down twister.

In the following description specific terms will be used for the sake of clarity, but it is to be understood that these terms are intended to be applied particularly to those specific forms of the invention which have been selected for illustration in the drawings, and that such terms are not intended to limit the scope of the invention, which is defined in the appended claims.

Referring to FIG. 1 of the drawings, the apparatus includes a pair of gripping crimping rolls 10 which are located just upstream of a stuffing box 11, which provides a zone of restriction, This particular form of the stufiing box crimping apparatus is not critical for purposes of this invention, but it may desirably assume the form as shown in the patent to Suggs, No. 2,860,400, the disclosure of which is incorporated herein by reference. It will be appreciated, of course, that the stuifer box 11 is ordinarily provided with a door 12, which is opened automatically under the influence of the internal pressure of yarn Y within the chamber 11, permitting such yarn Y to emerge from the chamber 11. In this manner, yarn which is fed between the nips of the rolls 10 is fed into a zone of restriction and is repeatedly buckled and folded upon itself and splayed out to form a multiplicity of successive V-shaped crimps in such zone.

As is apparent from FIG. 1, the yarn is initially fed along a predetermined path P toward the nip between the rolls 10, and as heretofore explained, the rolls 10 have a tendency to entrap the twist in the yarn Y, causing the twist to accumulate in the area upstream of the nip. The apparatus and method in accordance with this invention overcomes such tendency, forcing the rolls 10 to accept the twist as it is fed, without accumulating twist to any substantial degree upstream of the nip between the rolls 10. This apparatus comprises an upstream roller 13 which is closely adjacent to the nip between the rolls, and which is displaced upwardly as shown in the drawing, from the line of projection of the predetermined path P. Further, another roller 14 is located upstream of the roller 13 and is displaced below the predetermined path P. Thus, the rolls 13, 14 form the yarns into two arcuate portions, one beneath the roller 14 and one above the roller 13. These arcuate portions coact with one another to resist the tendency of the nip between the rolls 10 to hold back or strip back the twist in the yarn, and tend to force the rolls 10 to accept each turn of twist as it is fed toward the nip between the rolls. This greatly reduces the non-uniformity of crimp for reasons which will be explained in further detail hereinafter. The number of turns of twist per inch remain substantially constant as the yarn enters into the nip between the rolls 16L Referring to FIG. 2 of the drawings, this figure shows some of the details of a preferred form of apparatus in accordance with this invention. The number 20 designates the frame of the crimper, just upstream of the rolls 10, and supporting a carriage 21 which is slidable in an upstream and downstream direction on the machine frame 20. Carriage 21 includes an upright 22 to which is attached a yarn guard 23 which has a dual concave shape designed to extend into the space between the rolls 10 and as closely as possible into the nip between such rolls. The yarn guard 23 comprises a separator for the individual ends of yarn that are fed into the nip between the rolls 10. The downstream roll 13 and the upstream roll 14 are rotatably mounted on a pair of supporting bars 24, one at each end of the rolls. Each bar 24 is mounted for sliding movement relative to the upright 22, upstream and downstream. A thumbscrew 25 is provided for securing the member 24 in any desired fixed position.

The foregoing construction is particularly advantageous in permitting the operator to string up the machine. For this purpose, the rolls 13, 14 are displaced to an upstream location, thus moving the downstream roll 13 away from the yarn guard 23, giving the operator ample room to thread each yarn through its guide opening. Once the yarns have been threaded through the guide openings, the thumb screws 25 are loosened and the rllers 13, 14 are shifted in a downstream direction until the downstream roll 13 is closely adjacent to the yarn guard 23, after which thumb screw 25 is tightened. This arrangement is particularly advantageous since it is important to maintain the downstream roll 13 as close to the nip between the rolls as is possible. It will be appreciated that it is a matter of choice whether the upstream roll 14 is adjusted together with the downstream roll 13, or whether it is permitted to remain in fixed position.

FIG. 3 represents a diagrammatic illustration showing in exaggerated form the mechanism by which the rolls 10 cause the twist to be held back and to be accumulated upstream of the rolls. If the yarn Y were a rigid helix as shown, it is clear that the flat portion of the yarn would be gripped between the rolls 10 and this would tend to rotate the yarn Y about its longitudinal axis as it is forwarded through to the nip between the rolls 10. The material of the yarn Y must be deformed in passing through the rolls 10, and it has been discovered in ac cordance with this invention that the provision of the downstream and upstream rolls 13, 14 does in fact overcome the tendency of the crimping rolls 10 to back up the twist and to accumulate it upstream of the nip.

The importance of this invention is accentuated by reason of the mechanism encountered in the crimping of twisted multifilament yarns. When a multifilament yarn has a zero twist or a low twist, each yarn that is forced into the stuffing chamber or other crimp device, has a tendency to splay out, which means that the individual filaments of the yarn tend to balloon or to separate from one another in such a manner that each filament folds upon itself independently of many of the other filaments, producing a distinctive and highly desirable type of crimp. On the other hand, a highly twisted multifilament yarn does not have the tendency toward individual filament splaying, and such a yarn tends to be folded or buckled upon itself as a unit, with all of the filaments remaining closely packed together as they undergo the r folding and buckling operation. This produces a crimp of an entirely different character. Accordingly, it is highly undesirable to crimp successive lengths of yarn which vary radically as to the amount of twist, because the resulting crimps vary in magnitude and in type from one length to the next. In actual practice, wide variations of degree of twist have been found to have tremendous effect not only upon the crimp, but on the uniformity of fabrics produced from the crimped yarns, and upon the capacity or ability of the fabric to accept dyes uniformly.

FIG. 4 of the drawings shows this invention as applied to a down twister, which is provided with rolls 30, 31 forming a nip. As shown, yarns Y1, Y2 and Y3 are passed through the nip between the rolls and are then wound onto bobbins on a conventional down twister. It will be appreciated that if the yarn Y1 with an original twist of /z t.p.i.Z twist strips back at the roll to zero twist, and yarn Y2 with an original twist of /2 TPI-Z twist manages to pass at the roll with its original /2 t.p.i.Z twist, and yarn Y3 with an original twist of /2 t.p.i.Z twist accumulates as much as 2 /2 t.p.i.Z twist when stripped back and then surges past the rolls with such 2 /2 t.p.i.-Z twist, and it is desired to produce a 3-ply balanced yarn of Y2 t.p.i.S twist, any tendency of the rolls 30, 31 to back up the twist in the upstream direction of any one or more of the component yarns as shown in FIG. 4, will completely defeat the purpose of producing a uniform finished yarn or yarns which, when plied together, form a balanced twisted yarn.

Although specific embodiments of other forms of apparatus have not been illustrated, it will be appreciated that this invention has application not only in instances where yarns are passed through the nip between rolls, but are also applicable for edge crimping, gear crimping, air crimping, knit and deknit crimping, twisting, winding, warping, sizing, knitting and the like. The utility of this invention is applicable to any portion of the textile operation which has a tendency to back up the twist in the yarn.

Although this invention has been described with reference to a pair of rollers 13, 14 which are spaced apart from one another upstream and downstream along the yarn path, and are also displaced in a direction perpendicular to such path, it will be appreciated that various equivalent elements may be substituted for those specifically disclosed. For example, the rollers 13, 14 need not be rollers but may be stationary, and any other similar curved surfaces may be substituted, provided the straight line path of the yarn is converted into an arcuate form, and provided at least one or more arcuate forms are provided upstream in relation to the stripping back point. Preferably, the downstream arcuate portion of the yarn is as close as possible to the nip between the rolls or to the other device which has a tendency to cause the twist to back up and to be accumulated upstream. Although two such arcuate portions have been shown and described, one or more arcuate portions may be provided to advantage. Where rollers are provided, as shown, they may either be idler rollers or may even be driven, but if driven, they are preferably driven at the same speed as the yarn.

It will be appreciated that a primary advantage of this invention resides in minimizing the non-uniformity of the crimp, or minimizing the non-uniformity of a twisted yarn or knitted or woven product. The resulting uniformity makes the product much more valuable.

It is to be emphasized that the one or more coacting arcuate portions of the yarn upstream of the nip are to be sharply distinguished from sharp portions as would be created by passing the yarn over sharp edges, which does not accomplish the objectives of this invention.

Although this invention has been shown and described with reference to specific forms thereof, it will be appreciated that various modifications may be made, including the substitution of equivalent elements for those specifically shown and described, reversal of parts, and the use of certain elements independently of others, all without departing from the spirit and scope of the invention as defined in the appended claims.

The following is claimed:

1. Apparatus for equalizing twist in a yarn crimper having a frame and a pair of crimp rolls forming a nip, comprising a carriage movable along said frame toward and away from said nip, a yarn guide carried by said carriage and shaped to penetrate between said rolls close to said nip, a pair of spaced apart rollers carried by said carriage, and means for displacing at least one of'said rollers toward and away from said yarn guide.

2. The apparatus defined in claim 1 wherein means are provided for adjusting said yarn guide and said rollers up and down relative to said carriage.

3. In a process for texturizing twisted yarn in a texturizing apparatus having a tendency periodically to back up the twist and thus to :create periodic non-uniformity of twist, a process for rendering uniform the amount of twist per unit length of said yarn, said process including passing said yarn over a plurality of rolling surfaces spaced apart from one another upstream and downstream along the yarn path and also displaced in a direction perpendicular to said path, the downstream rolling surface being located closely adjacent to the texturizing apparatus.

4. The process as defined in claim 3 wherein the texturizing apparatus includes a pair of crimping rolls forming a nip and the downstream rolling surface is located immediately before the nip and within the area defined by the converging curved surfaces of the two rolls.

5. A process for controlling the amount of twist in a yarn per unit of length while said yarn is being advanced continuously to a device which tends to strip back the twist and thereby concentrate that twist causing it alternately to build up to an excessively high twist and then to surge past said device having alternately too high and too low twist and minimizing or entirely eliminating such surges, which process includes the steps of passing said yarn over a plurality of rollers upstream of said device, said rollers being spaced apart from one another upstream and downstream along the yarn path and also displaced in a direction perpendicular to said path, the downstream roller being located closely adjacent to said device.

References Cited by the Examiner UNITED STATES PATENTS 1,961,952 6/1934 Andrew 5790 2,811,770 11/1957 Young 2872 2,938,259 5/1960 Stock 2840 3,009,310 11/ 1961 Murchie et al 19--66 3,078,542 2/ 1963 McFarren et a1. 1966 3,101,521 8/1963 Rosenstein et al. 1966 3,103,903 9/1963 Broadn'ck et al. 57-90 X 3,120,692 2/ 1964 Crawford et a1 2872 3,145,429 8/1964 Resor 2872 X 3,178,794 4/ 1965 Carruthers 2872 DONALD W. PARKER, Primary Examiner.

J. PETRAKES, Assistant Examiner. 

3. IN A PROCESS FOR TEXTURIZING YARN IN A TEXTURIZING APPARATUS HAVING A TENDENCY PERIODICALLY TO BACK UP THE TWIST AND THUS TO CREATE PERIODIC NON-UNIFORMITY OF TWIST, A PROCESS FOR RENDERING UNIFORM THE AMOUNT OF TWIST PER UNIT LENGTH OF SAID YARN, SAID PROCESS INCLUDING PASSING SAID YAR OVER A PLURALITY OF ROLLING SURFACES SPACED APART FROM ONE ANOTHER UPSTREAM AND DOWNSTREAM ALONG THE YARN PATH AND ALSO DISPLACED IN A DIRECTION PERPENDICULAR TO SAID PATH, THE DOWNSTREAM ROLLING SURFACE BEING LOCATED CLOSELY ADJACENT TO THE TEXTURIZING APPARATUS. 